The present invention relates to stent technology. Advances of laser tissue welding in urinary tract repair are able to provide a rapid watertight seal and avoid potential lithogenesis caused by conventional sutures and staples. However, some problems have limited the clinical use of this technology, such as unreliable fusion strength, thermal damage of welded tissue and lack of a standard reference endpoint during welding procedures.
In U.S. Pat. No. 5,549,122, a method and apparatus for molding polymeric structures in vivo is disclosed. The structures comprise polymers that may be heated to their molding temperature by absorption of visible or near-visible wavelengths of light. By providing a light source that produces radiation of the wavelength absorbed by the polymeric material, the material may be selectively heated and shaped in vivo without a corresponding heating of adjacent tissues or fluids to unacceptable levels. The apparatus comprises a catheter having a shaping element positioned near its distal end. An emitter provided with light from at least one optical fiber is positioned within the shaping element. The emitter serves to provide a moldable polymeric article positioned on the shaping element with a substantially uniform light field, thereby allowing the article to be heated and molded at a desired treatment site in a body lumen.
In U.S. Pat. No. 5,141,516, a dissolvable anastomosis stent comprises a first member for receiving a first vessel stump, a second member for receiving a second vessel stump, and engaging means for engaging the first and second members where the engaging means and members are constructed of a biocompatible, non-toxic material which substantially completely dissolves mammalian bodily fluids. In addition, methods for preparing the dissolvable anastomosis stent and methods for surgical mammalian anastomoses using the dissolvable anastomosis stent are disclosed.
In U.S. Pat. No. 5,306,286, an absorbable stent for placement at the locus of a stenotic lesion which is flexible and compliance for safe and effective delivery to the cite of a coronary obstruction, for example, and so as to avoid arterial rupture or aneurysm formation while under continuous stress of a beating heart. The stent is expandable from a reduced diameter configuration, which facilitates delivery to the cite of a targeted arterial obstruction, to an expanded configuration when disposed within the targeted area The stent can be carried to the cite to be treated and expanded to its supporting diameter on any suitable expandable catheter such as a mechanically expandable catheter or a catheter having an inflatable balloon. The stent is formed so as to have a wall with pores and/or holes to facilitate tissue ingrowth and encapsulation of the stent. The stent will subsequently be bioabsorbed to minimize the likelihood of embolization of the dissolved material.
In U.S. Pat. No. 5,192,289, a stent or support is disclosed for use in the connection or anastomosis of severed vessels to support and seal the anastomotic site. The stent includes substantially cylindrical sections separated by a tapered transitional region. The cylindrical sections are provided with flanges that define tapered sealing surfaces. The dimensions of the two sections are selected to correspond with the diameter of the portions of the vessel to be supported. The stent is preferably made of polyglycolic acid and the dimensions of the stent are selected to provide optimal support and sealing characteristics with a minimum of damage to the epithelial lining of the vas deferens. In two preferred applications, the stent is used in anastomosis of the severed ends of a vas deferens and a Fallopian tube. A gauge is used to measure the severed ends and, in that manner, determine the appropriate dimensions of the stent.
In U.S. Pat. No. 5,425,739, a stent or support is disclosed for use in the connection or anastomosis of severed vessels to support and seal the anastomotic site. The stent includes substantially cylindrical sections separated by a tapered transitional region. The cylindrical sections are provided with flanges that define tapered sealing surfaces. The dimensions of the two sections are selected to correspond with the diameter of the portions of the vessel to be supported. The stent is preferably made of polyglycolic acid and the dimensions of the stent are selected to provide optimal support and sealing characteristics with a minimum of damage to the epithelial lining of the vas deferens. In three preferred applications, the stent is used in anastomosis of the severed ends of a vas deferens, a Fallopian tube, and a blood vessel. A gauge is used to measure the severed ends and, in that manner, determine the appropriate dimensions of the stent. A technique of forming porous stents, and other structures, is also disclosed.
In U.S. Pat. No. 5,662,712, a method and apparatus for molding polymeric structures in vivo is disclosed. The structures comprise polymers that may be heated to their molding temperature by absorption of visible or near-visible wavelengths of light. By providing a light source that produces radiation of the wavelength absorbed by the polymeric material, the material may be selectively heated and shaped in vivo without a corresponding heating of adjacent tissues or fluids to unacceptable levels. The apparatus comprises a catheter having a shaping element positioned near its distal end. An emitter provided with light from at least one optical fiber is positioned within the shaping element. The emitter serves to provide a moldable polymeric article positioned on the shaping element with a substantially uniform light field, thereby
In U.S. Pat. No. 5,762,625, a luminal stent inserted and fixed in a vessel, such as a blood vessel, so as to maintain the shape of the vessel, and a device for inserting and fixing the luminal stent, are disclosed. The luminal stent is formed of a yarn of bioabsorbable polymer fibers, which yarn is shaped in a non-woven non-knitted state in, for example, a meandering state, around the peripheral surface of an imaginary tubular member. The bioabsorbable polymer includes polylactic acid, polyglycol acid, polyglactin, polydioxanone, polyglyconate, polyglycol acid and a polylactic acid-.epsilon.-caprolactone copolymer. The device for inserting and fixing the luminal stent consists in a catheter having a balloon-forming portion in the vicinity of a distal end thereof and the luminal stent fitted on the balloon-forming portion and affixed to the balloon-forming portion by a bio-compatible material, such as an in vivo decomposable polymer, such as polylactic acid, water-soluble protein or fibrin sizing agent.
In U.S. Pat. No. 5,292,362, a composition is disclosed for bonding separated tissues together or for coating tissues or prosthetic materials including at least one natural or synthetic peptide and at least one support material which may be activated by energy and to methods of making and using the same.
In U.S. Pat. No. 5,527,337, a bioabsorbable stent is provided for placement at the locus of a stenotic portion of a body passage, such as a blood vessel, which is flexible and compliant for safe and effective delivery to the site of the stenotic portion of, for example, a blood vessel, and so as to avoid the disadvantages of chronic implantation, such as arterial rupture or aneurism formation while exposed to the continuous stresses of a beating heart. The stent is formed from a bioabsorbable material and is porous or has apertures defined there through to facilitate tissue ingrowth and encapsulation of the stent. The stent is encapsulated and biodegrades or bioabsorbs within a period of days, weeks or months as desired following encapsulation to thereby minimize the likelihood of embolization or other risks of the dissolved material and to avoid the disadvantages of chronic implantation.
In U.S. Pat. No. 5,209,776, a tissue bonding and sealing composition and method of using the same is provided. Disclosed is a composition for bonding separated tissues together or for coating tissues or prosthetic materials including at least one natural or synthetic peptide and at least one support material which may be activated by energy.
In U.S. Pat. No. 5,510,077, an intraluminal stent comprising fibrin treatment of restenosis is provided by a two stage molding process.
In U.S. Pat. No. 5,776,184, a device for delivery of a therapeutic substance into a body lumen including a polymer in intimate contact with a drug on a stent allows the drug to be retained on the stent during expansion of the stent and also controls the administration of drug following implantation. The adhesion of the coating and the rate at which the drug is delivered can be controlled by the selection of an appropriate bioabsorbable or biostable polymer and the ratio of drug to polymer.
In U.S. Pat. No. 5,659,400, a method for making an intravascular stent by applying to the body of a stent a solution which includes a solvent, a polymer dissolved in the solvent and a therapeutic substance dispersed in the solvent and then evaporating the solvent. The inclusion of a polymer in intimate contact with a drug on the stent allows the drug to be retained on the stent during expansion of the stent and also controls the administration of drug following implantation. The adhesion of the coating and the rate at which the drug is delivered can be controlled by the selection of an appropriate bioabsorbable or biostable polymer and the ratio of drug to polymer in the solution. By this method, drugs such as dexamethasone can be applied to a stent, retained on a stent during expansion of the stent and elute at a controlled rate.
During the past decade, the application of laser solders has greatly increased the bonding strength of laser fusion. Human albumin as a suitable solder agent were applied in several tissue welding such as urethra, ureters, skin and vascular due to its high safety. Several studies have demonstrated that the welding strength of laser tissue soldering depended on solder protein concentration. But, the technical problem still remains is the precise seromuscular apposition of tubular organs for accurate placement of the laser spot and uniform layering of the solder on the fusion surface during laser welding procedures. Those problems could cause fusion strength unreliable, wound healing process prolonged and increased scar tissue at anastomotic site so that anastomosis failed.
An insertable stent is provided for joining together and facilitating healing of adjacent tissues. Typically, the tissues are human tissues. Preferably, the insertable stent is made from completely non-toxic, bio- and blood-compatible materials, which are abstracted from the native serum and tissue of mammalian.
Each of the tissues employed herein defines an internal cavity. More preferably, the insertable stent comprises an insertable stent body which defines a bore. The bore permits fluid to pass through the insertable stent body.
In use, the insertable stent body is introduced into the internal cavities of the tissues. The insertable stent body fits within the confines of, and in contact with, each of the adjacent tissues. Most preferably, at least a portion of the insertable stent body is fusible to the adjacent tissues for facilitating healing of these tissues.
The preferred insertable stent of this invention is different than previous products in that it is made from mammalian serum and tissue, which is completely non-toxic, bio- and blood compatible, and is therefore substantially dissolvable. More specifically, during the healing process, at least a portion of the insertable stent body can be dissolved. Preferably, the insertable stent comprises a biocompatable insertable stent body.
The insertable stent body preferably includes chromophores such photothermal dye materials for absorbing electromagnetic radiation. The stent typically plays support, alignment, and soldering roles in the photothermal welding anastomosis processes. Thus photothermal welding is simplified and quickened, and the strength of welding is reinforced using the insertable stent. Suitable chormophoric dyes comprise indocyanine green, methylene blue, flourescein, and india ink, Prussian blue, copper phthalocyanine, eosins, acridine, iron oxide, jenner stain, and acramine yellow.
The insertable stent body preferably includes at least one therapeutic drug. Examples of such drugs are; antibiotics such as penicillin, ampiciline, and gentamycin; antiinflammatories such as glucocorticoids, dexamethasone; antithombotics such as heparain; vitamins and peptide growth factors such as epithelial growth factor and transforming growth factor; nerve growth factors, and insulin like growth factors.
The insertable stent body can preferably comprise a protein. For example, the insertable stent body can comprise any one or more of the following proteins: albumin, elastin, collagen, globulin, fibrinogen, fibronectin, thrombin, polypeptides, and fibrins. The insertable stent body can also comprise a carbohydrate, typically a sugar.
The insertable stent body preferably includes a radiopaque agent for preventing passage of x-rays or other radiation. Examples of such agents are; iothalamate meglumine, diatrizoate meglumine, diatrizoate sodium, and ioversol.
Furthermore, a method can also be provided for manufacturing an insertable stent for joining together and facilitating healing of adjacent tissues. The method preferably comprises first forming the insertable stent body and then forming a bore therewith for permitting fluid to pass therethrough.
In addition, a method is provided for using the insertable stent to join together and facilitate healing of the adjacent tissues. The method preferably comprises providing a plurality of tissues, each having an internal cavity and ends. Then, the above described insertable stent is introduced into the cavity of each tissue. Finally, the tissues are aligned so that the ends are located adjacent to each other, and the insertable stent body is fused to the tissues. In another embodiment of the invention, the tissues are fused to each other.
The step of fusing the insertable stent body to the adjacent tissues preferably comprises electromagnetically radiating the insertable stent body, which most preferably comprises a photothermal dye such as described above. After the fusing step is completed, preferably, the insertable stent body generally comprises at least one fused portion and at least one unfused portion. The method preferably includes the step of dissolving at least a portion of the unfused portion of the insertable stent body during healing of the tissues. More specifically, the insertable stent could be photothermally sensitive which allows it to absorb a range of wavelengths of a light source that produces a heat denatured reaction to coagulate and bind tissues at irradiation site, and which depends on what chromophores are added. The stent can produce heat denatured coagulation reaction by other energy sources. The stent is preferably designed so that the non-denatured portion is dissolved in body fluid in several minutes, and the denatured portion adheres to a bond site to form a seal circular ring to seal and support the vessel anastomosis site so that be it will be biodegradable during the healing process.
An insertable stent can be made from a mammalian serum and/or a tissue source which comprises hydrolyzable protein that is a group of non-toxic, bio- and blood-compatible natural material. The insertable stent, including chromophores, plays a significant support role in the vessel intralumen and plays a soldering role in the energy welding processes. The non-denatured portion of the stent is typically dissolved in body fluid after energy welding anastomosis as so to not effect the vessel fluid flow and to be biodegradable.
The insertable stent can be used for temporal connection and supporting vessels during anastomosois processes. The anastomostic techniques are conventionally those such as suturing, stapling, gluing and energy welding processes.
The insertable stent with chromophores which is a photothermal sensitive insertable stent will be used for temporal connection and supporting vessels during end to end anastomosis techniques which comprise several sutureless vessel anastomosis techniques using energy welding to produce heat coagulation effect. The anastomostic techniques consist of conventional suturing, stapling, gluing and energy welding processes.
The stent will be as a drugs carrier to increase local drug concentration in the intraluminal of vessel for therapeutic and preventing the surgical complication as wound healing delayed, stricture of anastomosis and/or diseases. The method can also include the step of releasing at least a portion of the therapeutic drug from the insertable stent body. This will assist with the healing of the tissues.
The tissues are preferably selected from a group consisting of blood vessels, gastrointestinal, genitourinary, reproductive, respiratory tubes, grafts, and synthetic prosthetics. At least one of the tissues will preferably expand when the insertable stent is introduced into the cavity.
The fusing preferably comprises photothermal bonding such as laser welding. The fusing can also comprise thermal bonding facilitated by bipolar electrodes or magnetic and microwave thermal welding. The fusing can also comprise chemical bonding without an energy source which is extrinsic to the tissues, such as with biocompatable sealants. Examples of such sealants are cyanoacrylate glue and fibrin glue. The fusing can also comprise photochemical bonding, such as riboflavin fusion.